A comparison of the agreement,internal consistency,and 2-day test stability of the InBody 720, GE iDXA,and BOD POD® gold standard for assessing body composition

The study compared the agreement, internal consistency, and measurement stability of the GE iDXA, BOD POD, and InBody 720. Body composition of 43 men and 37 women (31.4 ± 10.7 years; 90% Caucasian and 10% other) was assessed in triplicate using each method over two different days. Mean percent body fat (% BF) of the participants was different for all three machines (27.6 ± 10.0% [GE iDXA)] 25.6 ± 10.4% [BOD POD], and 21.3 ± 10.6% [InBody 720]; p < .05). The coefficient of variation for same day repeated measures was 1.06% (GE iDXA), 3.29% (BOD POD), and 2.97% (InBody 720). The coefficient of variation for 2-day repeated measures was 1.81% (GE iDXA), 4.61% (BOD POD), and 4.24% (InBody 720). The difference between the GE iDXA and BOD POD was within acceptable variability, while the InBody 720 significantly underestimated % BF. The internal consistency was highest for the GE iDXA, followed by the InBody 720, and then the BOD POD.     

Associations Between Sexting Behaviors and Sexual Behaviors Among Mobile Phone‐Owning Teens in Los Angeles

The implications of teen sexting for healthy development continue to concern parents, academics, and the general public. Using a probability sample of high school students (N = 1,208) aged 12–18, the prevalence of sexting, associations with sexting, and associations between sexing and sexual activity were assessed. Seventeen percent both sent and received sexts, and 24% only received sexts. Sending and receiving sexts were positively associated with each other and both behaviors were associated with having peers who sext. Lifetime reports of sexual intercourse, anal sex, oral sex, and recent unprotected sex were positively associated with reports of texting 300 or more times per day, only receiving sexts, and both sending and receiving sexts.     

An intensification approach to double-block algebra: A pilot implementation of Intensified Algebra in a large urban school district

Double-block instruction has become a popular strategy for supporting struggling mathematics students in algebra I. Despite its widespread adoption, little consistent evidence supports the attributes of a successful double-block design or the effectiveness of this instructional strategy. In this study, the authors examine a pilot implementation of a double-block strategy—instantiated in the program Intensified Algebra—that combines core algebra content with insights from research on how students learn mathematics and explicit noncognitive supports focused on key attitudes, beliefs, and behaviors essential to student success. The results of the study show that, when implemented with fidelity, participation in the program significantly increased student achievement on the state end-of-course algebra I assessment.     

Effect of a randomised 12-week resistance training programme on muscular strength,cross-sectional area and muscle quality in women having undergone Roux-en-Y gastric bypass

The purpose of this study was to examine the effect of a 12-week resistance training programme on fat-free mass (FFM), muscle cross-sectional area, muscular strength and muscle quality in women who underwent Roux-en-Y gastric bypass surgery. Participants were 16 women (mean age = 44.9 ± 10.2 years) from bariatric surgical groups who were randomly assigned into either a control or an intervention group. Air displacement plethysmography measured FFM and magnetic resonance imaging measured quadriceps muscle cross-sectional area and whole thigh muscle cross-sectional area. Muscular strength and quality was assessed using an estimated 1-Repetition Maximum assessment. All measurements were collected twice, at baseline and at a 12-week follow-up. There were significantly greater improvements in leg press strength (mean differences = 55.4%, P < 0.001, Cohen’s d = 2.4), leg extension strength (mean differences = 18.0%, P = 0.014, Cohen’s d = 0.86) and leg press muscle quality (mean differences = 54.5%, P < 0.001, Cohen’s d = 1.9) in the intervention group compared to the control group following the resistance training programme. The resistance training intervention significantly improved muscular strength and quality; however, it did not illicit changes in FFM or muscle cross-sectional area in women who underwent Roux-en-Y gastric bypass surgery.     

Comment on ‘Ventilation and blood lactate increase exponentially during incremental exercise’ : A reply

Oar force and oar angle data resulting from a 6‐min maximal rowing ergometer test undertaken by novice (n = 9), good (n ‐ 23) and national (n = 9) level male rowers, were used to identify biomechanical performance variables which accurately discriminated between rowers of differing ability levels. The variables included two work capacity measures, mean propulsive power output per kilogram of body mass (W kg^‐1) and propulsive work consistency (%), and two skill variables, stroke‐to‐stroke consistency (%) and stroke smoothness (%). Discriminant function analysis indicated the presence of two functions, both of which clearly indicated the importance of mean propulsive power output per kilogram of body mass as a discriminating variable. Function 2 gave greater weight to stroke‐to‐stroke consistency and stroke smoothness than function 1; however, function 1 was the most powerful discriminator. Classification procedures were used to predict the ability level to which a rower most likely belonged and involved defining the ‘distance’ between each rower and each ability level centroid, with the rower being classified into the ‘nearest’ ability level. These procedures indicated that 100% of the elite, 73.9% of the good, 88.9% of the novice and 82.9% of all rowers were correctly classified into their respective skill levels. Stepwise discriminant analysis included the variables in the following order: mean propulsive power output per kilogram of body mass, stroke‐to‐stroke consistency, stroke smoothness and propulsive work consistency (P < 0.001). The results of this study indicate that biomechanical performance variables related to rowing capacity and skill may be identified and used to discriminate accurately between rowers of differing skill levels, and that, of these variables, propulsive work consistency is the least effective discriminator.     

Distribution of Practice in Motor Skill Acquisition: Different Effects for Discrete and Continuous Tasks

Abstract

Research on the benefits of distributed practice for the acquisition and retention of motor skills has a long history. The majority of this research has involved skill acquisition of continuous tasks. However, there is some evidence to suggest that distribution of practice effects are quite different for discrete tasks than for continuous tasks. In the present study, we used a single task, formed discrete and continuous versions of the task, and examined how acquisition and retention were affected by the length of inter-trial interval. The basic task was a movement timing task that involved either one timing estimate per trial (the “discrete” version) or twenty successive estimates per trial (the “continuous” version). Separate groups of subjects learned one version of the task under either distributed (25 s inter-trial intervals) or massed (0.5 s inter-trial intervals) practice conditions. Both massed and distributed retention trials were performed on the same version of the task according to a double transfer design. The results confirmed the apparent disparity: Acquisition and retention were facilitated by distributed practice on the continuous task, but by massed practice on the discrete task. These results were discussed in terms of the role of the inter-trial interval in discrete and continuous tasks.     

Physiological Effects of Deep Water Running following a Land-Based Training Program

Abstract

The purpose of this study was to examine differences in knowledge representation and problem solutions in expert and novice youth baseball players. Ninety-four players in two age divisions, 7–8 years of age and 9–10 years of age, were assigned to three levels of expertise: high; average; and low skilled. Each subject participated in an interview session to elicit knowledge representation and solutions to five different defensive game situations. Interviews were transcribed and analyzed for content, solution to the problem, errors in problem solution, and qualitative trends. The frequency of advanced solutions to each of the five situations were analyzed in separate chi-square tests for age and expertise. Differences among the levels of expertise were found for the accuracy of solutions to three complex situations. Age was significant for only one situation. Patterns of knowledge content accessed during advanced and less advanced responses indicated both experts and novices were in a beginning stage of developing baseball knowledge structures. Errors in problem solutions indicated children had difficulty monitoring critical conditions and making correct inferences. Players' and teammates' ability to execute baseball skills seemed to influence the content and structure of tactical knowledge accessed during problem solution.     

Fitting Structural Equation Model Trees and Latent Growth Curve Mixture Models in Longitudinal Designs: The Influence of Model Misspecification

When conducting longitudinal research, the investigation of between-individual differences in patterns of within-individual change can provide important insights. In this article, we use simulation methods to investigate the performance of a model-based exploratory data mining technique—structural equation model trees (SEM trees; Brandmaier, Oertzen, McArdle, & Lindenberger, 2013)—as a tool for detecting population heterogeneity. We use a latent-change score model as a data generation model and manipulate the precision of the information provided by a covariate about the true latent profile as well as other factors, including sample size, under the possible influences of model misspecifications. Simulation results show that, compared with latent growth curve mixture models, SEM trees might be very sensitive to model misspecification in estimating the number of classes. This can be attributed to the lower statistical power in identifying classes, resulting from smaller differences of parameters prescribed by the template model between classes.     

‘I’m just not that comfortable with technology’: student perceptions of and preferences for Web 2.0 technologies in reflective journals

Encouraging reflective practice and developing reflective practitioners is a goal of many disciplines in higher education. A variety of pedagogical techniques have been used to promote critical reflection including portfolios, narratives and reflective journals. Over the past decade, the use of Web 2.0 technologies with students has been increasingly adopted in higher education settings and many educators have integrated these technologies into reflective assignments. These educators assume that students, who are members of the Net Generation, are technologically savvy and have the ability to integrate the use of Web 2.0 technologies into learning. However, while there have been studies examining the outputs of reflective assignments using Web 2.0 technologies such as blogs, e-portfolios and wikis, there has been little research examining whether or not students actually use technology for these types of assignment if given the choice. Therefore, the purpose of this study was to explore if technology was appropriated or rejected by students for a reflective journaling assignment. Results are based on a content analysis of 42 student journaling assignments and interviews with eight students. Findings suggest that (1) students are not as technologically competent as assumed; (2) students chose to use basic/fundamental technologies (e.g. word processing) because they viewed it as the easiest way to complete the reflective journaling assignment; (3) student perceptions of what makes an assignment ‘good’ influenced their choice to use Web 2.0 technologies; and (4) overarching student perceptions of higher education and learning impacted their appropriation of technology. Implications are discussed and recommendations for both research and practice are made.